Synthetic petrolatum compositions

ABSTRACT

Petrolatum-like products are prepared by combining a distillate lubricating oil, a slack wax derived from a distillate lubricating oil and a wax crystal modifying additive having an intrinsic viscosity in the range of about 0.05 to about 0.3 dl/g and selected from the group consisting of amorphous polyethylene, amorphous polypropylene, copolymers thereof, halogenated homopolymers and copolymers thereof, and copolymers of 3 to 40 molar proportions of ethylene per molar proportion of an ethylenically unsaturated monomer having the general formula:   WHEREIN X is selected from the group consisting of hydrogen, halogens and C1 to C5 alkyl groups; Y is selected from the group consisting of -OOCR, -OOCR and -COR groups; Z is selected from the group consisting of -COOR and -R; and R is selected from the group consisting of hydrogen and C1 to C10 alkyl groups.

United States Patent [191 Macleod Oct. 9, 1973 SYNTHETIC PETROLATUM COMPOSITIONS [76] Inventor: David M. Macleod, 835 Lakeshore i Rd., Sarnia, Ontario, Canada [62] Division of Ser. No. 16,980, March 5, 1970, Pat. No.

[52] US. Cl 252/56 R, 252/11, 252/308, 260/285 AV, 424/83 [51] Int. Cl Cl0m 1/28 [58] Field 01 Search 252/11, 52, 54.6, 252/56 R, 308, 316; 424/78, 83; 260/285 AV [56] References Cited UNITED STATES PATENTS 2,133,412 10/1938 Anderson 260/285 A 2,628,187 2/1953 Frohmader et a1. 252/56 R 2,775,561 12/1956 Frohmader et al. 252/59 3,215,599 11/1965 Thau et al 424/83 FOREIGN PATENTS OR APPLICATIONS 976,716 12/1964 Great Britain 1,014,075 12/1965 Great Britain Primary ExaminerPatrick P. Garvin Assistant Examiner-W. Cannon Attorney-Roy J. Ott

[5 7] ABSTRACT Petrolatum-like products are prepared by combining a distillate lubricating oil, a slack wax derived from a distillate lubricating oil and a wax crystal modifying additive having an intrinsic viscosity in the range of about 0.05 to about 0.3 dl/g and selected from the group consisting of amorphous'polyethylene, amorphous polypropylene, copolymers thereof, halogenated homopolymers and copolymers thereof, and copolymers of 3 to 40 molar proportions of ethylene per molar proportion of an ethylenically unsaturated monomer having the general formula:

wherein X is selected from the group consisting of hydrogen, halogens and C to C alkyl groups; Y is selected from the group consisting of OOCR, OOCR and COR groups; Z is selected from the group consisting of COOR and R; and R is selected from the group consisting of hydrogen and C to C alkyl groups.

8 Claims, No Drawings SYNTHETIC PETROLATUM COMPOSITIONS This is a division, of application Ser. No. 16980, filed Mar. 5, 1970 now U.S. Pat. No. 3,642,635.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to improved petrolatum-like products. More specifically, it relates to products prepared for distillate lubricating oil, distillate lubricating oil slack wax and a wax crystal modifying additive having an intrinsic viscosity in the range of about 0.05 to about 0.3 dl/g.

2. Description of the Prior Art Natural petrolatums are unctuous mixtures of wax and oil derived from the residual fraction after distillation of certain crude oils. They are soft, oily, semisolids which have many uses including ink formulations, rubber compounding, protective waterproof coatings, leather dressings, medicinal ointments, etc. Their properties may be generally summarized as follows:

Melting Point ll80F. Cone Penetration at 77"F. 75-200 mm/lO Viscosity at 210F. 65-130 SUS Flash Point Above 350F.

C010! Ranging from white to almost black Crystallinity Very fine structure Fibrosity Forms grease-like fibres when pulled Extensibility Long fibres usually formed Recoil Films of fibres do not tend to flow into drops or contract as liquid oil or rubber like materials do.

Natural petrolatums are in restricted supply and comparatively high in price. It would be desirable to manufacture petrolatums by mixing readily available and lower cost lubricating oils and lubricating oil slack waxes, but the properties of such mixtures do not match those of natural petrolatums.

Pour point depressants, otherwise know as wax crystal modifiers, are well known in the art. These modifiers have been formed by copolymerizing ethylene and vinyl esters of lower fatty acids, particularly vinyl acetate, as described for example in U.S. Pat. Nos., 3,048,479; 3,093,623 and 3,131,168; or by copolymerizing ethylene with alkyl acrylates as described in Canadian Patent No. 678,875 and U.S. Pat. No. 3,126,364.

Similarly, British Patent No. 993,744 discloses the use of polyethylene, polypropylene and copolymers thereof as pour point depressants, U.S. Pat. No. 3,337,313 discloses the use of halogenated pour point depressants and copending commonly assigned application Ser. No. 744,667, filed July 15, 1968, discloses the use of copolymers of ethylene with unsaturated ketones as pour point depressants. However, heretofore these wax crystal modifiers and similar compositions have not been successfully used in producing petro1atum-like products. Thus, small amounts of crystalline polyethylene, butyl rubber and high molecular weight ethylene-vinyl acetate copolymers have been found to alter the crystal size of wax-oil mixtures to match natural petrolatum, but the other properties were not satisfactory, e.g. cyrstalline polyethylene and high molecular weight ethylene-vinyl acetate copolymcr failed to improve the brittleness and extensibility, and butyl rubber, while satisfactory in these respects, resulted in objectionable recoil.

Recently, British Patent No. 1,014,075 disclosed a composition comprising either ethylene propylene copolymer or vinyl acetate/ethylene copolymer (having an inherent viscosity in the range of 0.45 to 1.50) in combination with petroleum wax and oil for use as a protective coating. However, said components result in a poor quality petrolatum with crystalline, grainy wax particles. Furthermore, the fact that the composition was described as being capable of bleeding oil indicates that the compatibility of the components is poor.

U.S. Pat. No. 2,133,412 discloses the manufacture of petrolatum-like products from distillate paraffin wax, mineral oil and polyisobutylene having a molecular weight of 2,000 to 10,000. However, the resulting products of this patent are also characterized by crystalline, grainy wax particles and oil bleeding is observed when polyisobutylene having a molecular weight of about 2,000 are employed.

SUMMARY OF THE INVENTION It has now been discovered that all of the aforementioned polymers and copolymers which are amorphous and which have an intrinsic viscosity in the range of about 0.05 to about 0.3 dl/g can be advantageously used to produce synthetic petrolatums. More specifically, it has now been discovered that good replacements for natural petrolatum are obtained by combining a distillate lubricating oil, a distillate lubricating oil slack wax and a crystal modifying additive, having an intrinsic viscosity in the range of about 0.05 to about 0.3 dl/g, and selected from the group consisting of amorphous polyethylene, amorphous polypropylene, copolymers thereof, halogenated homopolymers and copolymers thereof, copolymers of 3 to 40 molar proportions of ethylene per molar proportion of an ethylenically unsaturated monomer having the general formula:

wherein X is selected from the group consisting of hydrogen, halogen and C to C alkyl groups; Y is selected from the group consisting of OOCR, COOR and COR groups; Z is selected from the group consisting of COOR and -R; and R is selected from the group consisting of hydrogen and C to C alkyl groups and mixtures thereof. More particularly, it has been found that a combination of 15 to 50 wt. distillate lubricating oil slack wax, 40 to 84 wt. distillate lubricating oil and l to 20 wt. of said crystal modifying additives can produce a synthetic petrolatum whose properties surpass those of any of the above mentioned synthetic products.

The distillate lubricating oils used in preparing the unctuous products of this invention are those distillate oils generally characterized by a boiling range of about 650F. to about 1150F. A.E.T. (atmospheric equivalent temperature) and a viscosity at 210F. in the range of about 40 to 180 SUS. Preferred are those oils having a boiling range of about 850F. to l F. and a viscosity at 210F. of about 70 to SUS.

The wax component of this invention is generally a slack wax derived from a distillate lubricating oil having a boiling range of about 650F. to 1150F. A.E.T.

(atmospheric equivalent temperature). The wax itself has a melting point in the range of about 100F. to about 170F., an oil content of about 5 to about 50 percent, and a viscosity at 210F. in the range of about 35 to about 80 SUS. Preferred is a wax having a melting point in the range of about 130F. to about 165 F. and a viscosity at 210F. in the range of about 55 to about 75 SU S, derived from a distillate oil having a boiling point in the range of about 800F. to about 1100F.

The crystal modifying additive of this invention must have an intrinsic viscosity in the range of about 0.05 to about 0.3, preferably 0.1 to about 0.29 dl/g, in order to produce a product having the desired characteristics.

Intrinsic viscosity was herein calculated from the following relationship in which specific viscosity was determined at 100F. in toluene:

n r nsic VISCOSI I l S y Cone. of Solution Although the polymers useable as crystal modify-ing additives in accordance with this invention are low molecular weight polymers, use of actual molecular weight numbers in identifying the polymers has been found to be practically meaningless in specifying the type of polymer useful in accordance herewith. Molecular weight numbers are at most an extremely poor and inconclusive means of identifying the polymers. The methods which measure molecular weight directly, such as cryoscopic (e.g. Rast Method), ebulliscopic (e.g. Menzies-Wright Method) or osmometric techniques, are unreliable in the low molecular weight range of the useful polymers. The effects that must be measured by such techniques become progressively smaller as molecular weight increases, and error introduced by low molecular weight contaminants becomes important in such techniques as applied to lower molecular weight polymers. For example, using these techniques molecular weights for the same given polymer have differed twofold depending upon the molecular weight technique used.

For these reasons, the polymers are specified by means of physical properties such as intrinsic viscosity and crystallinity characteristics.

The amorphous polymers of this invention are generally characterized as having less than percent crystallinity as determined by differential thermal analysis and a solubility in toluene at room temperature (e.g. 77F.) greater than percent.

Suitable amorphous polyethylene, amorphous polypropylene and amorphous copolymers of ethylene and propylene in any relative mole ratio may be prepared by the well-known Ziegler polymerization process, e.g. U.S. Pat. No. 3,051,690, or may be obtained as a commercially available chemical commodity. The halogenated homopolymers and copolymers thereof have a halogen weight content of about 4 to 35 percent, preferably 10 to percent, based on the total 'weight of the halogenated polymer, and can be prepared by the chlorination methods described in U.S. Pat. No. 3,337,313. The preferred halogen is chlorine.

The copolymers of ethylene and an ethylenically unsaturated monomer which are useful for blending into the aforementioned waxes and oils are those having an ethylene'content of about 3 to 40, preferably 3 to 20 molar proportions per molar proportion of monomer. The monomer, having the general formula:

where X and Z are hydrogen and Y is OOCR, includes vinyl alcohol esters of C to C monocarboxylic acids, preferably C to C monocarboxylic acids. Examples of such esters include vinyl acetate, vinyl isobutyrate, vinyl laurate, vinly myristate, vinyl palmitate, etc. When Y is COOR, such esters include methyl acrylate, methyl methacrylate, isobutyl acrylate, lauryl acrylate, C Oxo alcohol esters of methacrylic acid, etc. Examples of monomers where X is hydrogen and Y and Z are COOR groups include mono and di-esters of unsaturated dicarboxylic acids such as: mono C Oxo fumarate, di-C Oxo fumarate, di-isopropyl maleate, di-lauryl fumarate, ethyl methyl fumarate, etc. When Y is COR, said monomer includes vinyl methyl ketone, vinyl isobutyl ketone, vinyl n-octyl ketone, vinylisooctyl ketone, vinyl dodecyl ketone, vinyl-phenyl ketone, vinyl-naphthyl ketone, vinyl-cyclohexyl ketone, 3-pentene-2-one, (i.e. Z is methyl, X is hydrogen and Y is acetyl), etc. These copolymers can be prepared using the techniques used for ethylene-vinyl ester copolymerizations, e.g. by copolymerizing a mixture of monomer and ethylene in the presence of a suitable catalyst such as a peroxy compound like di-tertiarybutyl-peroxide at a temperature in the range of about 200 to about 300F. and a pressure in the range of about 700 to 5000 pounds. Similarly, the methods described in U.S. Pat. Nos. 3,048,479; 3,l3l,l68; 3,093,623; and 3,254,063; etc. can also be used.

The compositions of this invention can be prepared by methods known in the art which do not constitute a part of this invention. For example, the oil and wax can be premixed at a temperature in the range of about 220F. to about 300F. and then the crystal modifying additive can be added in solid or liquid form or all three components can be added simultaneously. The mixture is then agitated at the above temperatures for a period ranging from about 15 minutes to one hour and then cooled.

Generally the distillate lubricating oil will form about 40 to about 84, preferably 50 to about wt. of the total composition; the distillate lubricating oil slack wax will form about 15 to about 50, preferably 20 to about 40 wt. of the total composition; and the crystal modifying additive will form about 1 to about 20, preferably 3 to 10 wt. of the total composition.

It is to be understood that while the compositions of this invention are usually produced by combining dewaxed distillate lubricating oils and distillate lubricating oil slack wax, it would be possible to produce the same compositions by taking an equivalent lubricating oil which has not been dewaxed (but which normally contains only about l0 percent wax) and adding additional slack wax in order to bring the total wt. of the wax in the final composition within the range contemplated by this invention, and that a composition formed in this manner is contemplated in the scope of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples, which are set forth for purposes of illustration and not limitation, may serve to illustrate the preparation and properties of certain preferred embodiments of this invention.

EXAMPLE 1 65 grams of distillate lubricating oil and 30 grams of distillate lubricating oil slack wax were placed in a laboratory mixer maintained atwa temperature of 250F.

vinyl acetate content of 32 percent and an intrinsic viscosity of 0.261 dl/g.

(Crystalline) Polyethylene A (Canadian Industries Ltd., Grade 170 F) has a density of 0.919, a melt index of 8.5, a molecular weight of about 12,000 to about 20,000 by viscosity average method, an intrinsic viscosity of 0.391 and a solubility in toluene at 77F. of less than 1 percent.

(Crystalline) Polyethylene B (Allied Chemical Grade AC6) has a density of 0.92, a molecular weight quoted by the manufacturer as 2000, an estimate molecular weight by viscosity average method of 2000, an intrinsic viscosity of about 0.159 dl/g and a solubility in toluene at 77F of less than 1 percent.

- ag gi i P? z i g z $2 Ethylene vinyl acetate Copolymer B (used in comg i i i agl a e t or ntlmu i parative Petrolatum D and purchased under the trade :Side F il g 6 empea Se name Elvax 150) has an intrinsic viscosity of 0.761 dl/g s that used in the workin exam les In Table l are set forth certain preferred embodig i i l g sggj 1 014 075 g p ments of this invention as well as comparative petrola- 0 n ls tum compositions. The compositions were all prepared The y -P py Copolymer of comparanve using the procedure described in Example 1, which was petrolatum E was Purchased under the trade name of presented above in greater detail for illustration pur- Vlstakm 404 and has an mmnslc vlscoslty of about poses 1.421 dl/g. (which is within the range mentioned on TABLE 1 Comparative petrolatums Exam- Exam Exam- Exam- Components ple l ple Z A B C D E F G ple 3 ple 4 (g) (g) (g) (g) (g) (g) (g) (g) (g) (s) OII A 65 65 68 65 69.5 65 68 65 65 65 65 Wax A 30 30 30 30 30 30 30 30 30 30 Amorphous polypropylene 5 Ethylene/vinyl acetate copolymer A 5 (Crystalline) polyethylene A 2 (Crystalline) pol yethylene B 5 Butyl rubber 0.5 Ethylene/vinyl acetate copolymer B. 5 Ethylene propylene copolymer...... 2 Polyisobutylene A 5 Polyisobutylene B 5 (Amorphous) polyethyl e ne C 5 Ethylene/isobutyl acrylate copolymer 5 nadian Crude. It has a viscosity at F. of 3600 SUS,

a viscosity index of 70, a boiling range of 900F. to 1 100F. A.E.T., a solid point of 20F. and a viscosity at 210F. of SUS.

Wax A is a slack wax from an overhead fraction derived from Western Canadian Crude having a boiling range of 900F. to 1 100F. A.E.T. The wax has a melting point of F., a viscosity at 210F. of 75 SUS, an oil content of 20 percent and a cone penetration of 26 mm/ 10.

Amorphous polypropylene (Grade Eastobond MSL) has a ring and ball softening point of 198F., a melting viscosity of 3000 cp at 300F., an estimated molecular weight of 8000 by viscosity average method and an intrinsic viscosity of 0.273 dl/g.

Ethylene vinyl acetate Copolymer A used in Example 2 has a melt index above 5000, a molecular weight of about 2000 to about 3000 by cryoscopic methods, a

page 2, lines 3-5 of British Patent No. 1,014,075).

Polyisobutylene A has an intrinsic viscosity of 0.250 and a molecular weight ranging from about 8,000 to 10,000.

Polyisobutylene B has an intrinsic viscosity of 0.056, a molecular weight of about 2000 and is sold under the trade name Petrofin 2000.

(Amorphous) polyethylene C of Example 3 is a polyethylene homopolymer product from the peroxide catalyzed polymerization of ethylene. It has a number average molecular weight of about 2000, an intrinsic viscosity of about 0.1 13 dl/g and a solubility in toluene at 77F. greater than 25%.

The ethylene isobutyl acrylate copolymer used in Ex ample 4 has a number average molecular weight of about 3300 and an intrinsic viscosity of about 0.237 dl/g. It was prepared by the free radical peroxide copolymerization of 7.2 moles ethylene per mole of isobutyl acrylate.

The properties of the above synthetic petrolatums of Table l and natural petrolatum are shown in Table II.

TABLE II Intrinsic Visc. of

crystal Viscosity Cone pene modifying at 210 F. tration Composition agent, dl/g SUS 77 F. mm/lO Crystallinity Fibrosity Extensibility Recoil Oil bleeding Example 1... 0.273 220 120 Microcrystal- Fibrous Large None None.

line Example 2 0.261 120 120 Microcrystal Fibrous Large None None.

line Natural 88 180 Microcrystal- Fibrous Large None None.

petrolatum line Comparative 0.391 300 83 Microcrystal- Brittle Small None None.

petrolatum A line Comparative 0.159 120 78 Microcrystal- Brittle Small None None.

petrolatum B line Comparative 150 110 Microcrystal- Fibrous Large Large None. petrolatum C line Comparative 0.761 Crystalline Grainy None None Slight.

petrolatum D Comparative 1.421 Microcrystal- Rubbery Very Very None.

petrolatum E line Large Large Comparative 0.250 Crystalline Grainy None None None.

petrolatum F v Comparative 0.056 Crystalline Grainy Slight None Slight.

petrolatum G Example 3 0.113 Microcrystal- Fibrous Large None None.

7 line Example 4 0.237 Microcrystal- Fibrous Large None None.

line

TABLE lIl.Comparison of Petrolatum With Wax Oil Mixtures Properties Cone pen at 77 F Composition mm/ 10 Crystallinity Fibrosity Extensibility Recoil Natural petrolatum 180 Microcrystal- Fibrous Large None.

line. wax A, 50% oil A Large crystals Grainy Small None. 30% wax A, 70% oil A 1 10 Large crystals Grainy Small None. 10% wax A, oil A 198 Large crystals Grainy Small None.

lelrolutum- Residual tmction, M.l. F., Viscosity at 210 F. 88 SUS, ()il Content 50%.

'lAHLF. lV. Use of Different Distillate Oils and Waxes With Amorphous Polypropylene Vis. at (on- (one pen. 210 F. gealing at 77 F. Extensi- Oil Composition SUS pt. F. mm/l0 Crystallinity Fibrosity bility Recoil bleeding Color.

30% wax B. 65% oil A. 5% 179 134.0 120 Microcrystal- Fibrous Large None None Dark amorphous polypropylene. line. brown. 30% wax B, 65% oil BF 5% 149 133.0 124 Microcrystal Fibrous Large None None Dark amorphous polypropylene. line. brown. 30% wax B, 65% oil C, 5% 125 131.0 123 Microcrystal- Fibrous Large None None Light amorphous polypropylene. line. yellow.

Distillate wax BA slack wax from an overhead fraction, derived from Western Canadian Crude. Boiling range 800 to 1000 F., AET( MP F., Viscosity at 210 F., 63 SUS, Oil content 20%, Cone pen. 26 mm/lO.

2 Distillate oil B-From Western Canadian Crude. Viscosity at 100 F., 550 SUS, VI 90. Boiling range 800 to 1000 F., AET, Solid point 20 F., Viscosity at 210 F., 72 SUS.

Distillate oil C Derived from Tia Juana 102 Crude Oil, viscosity at 100 F., 900 SUS, VI 68. Boiling range 850 to 1050 F., AET, Solid point 20 F., Viscosity at 210 F., 80 SUS.

2,133,412 resulted in a petrolatum with grainy crystalline particles which exhibited slight oil bleeding when As can be seen from Table II, only the compositions of this invention exhibit all of the properties of natural petrolatum. The use of crystalline polyethylenes A and 55 the lower molecular weight polymer was used.

B resulted in petrolatum of inferior fibrosity and extensibility; the use of butyl rubber resulted in objectional recoil; the use of an ethylene/vinyl acetate copolymer B having an inherent viscosity between 0.45 and 1.50 for 0.25 wt. copolymer in toluene at 30C. (which is equivalent to an intrinsic viscosity range of 0.53 to 1.59 dl/g) as disclosed in British Patent No. 1,014,075 resulted in crystalline grainy wax particles and slight oil bleeding; the use of ethylene propylene copolymer of the type disclosed in the British patent, having an intrinsic viscosity outside of the critical range, resulted in objectional fibrosity and recoil; and the use of polymerized isobutylene of the type disclosed in U.S. Pat. No.

That simple mixtures of oil and wax will not exhibit the properties of natural petrolatum can be seen from Table III.

65 are adjusted to equal the softness, or penetration, of the petrolatum. The same effect is found with other waxes and oils of different melting points and lubricating oil boiling ranges.

EXAMPLES 5, 6 and 7 In accordance with the procedure of Example 1, three additional 100 gm petrolatum compositions were prepared using amorphous polypropylene and different distillate lubricating oils and waxes. The resulting products and their properties, which are the same as natural petrolatum, are shown in Table IV.

While particular embodiments of this invention are shown in the examples, it will be understood that the invention is obviously subject to the variations and modifications disclosed above without departing from its broader aspects and, therefore, it is not intended that the invention be limited to the specific modifications which have been given above for the sake of illustration, but only by the appended claims.

What is claimed is:

l. A synthetic petrolatum composition comprising:

a. about 40 to about 84 wt. distillate lubricating oil;

b. about to about 50 Wt. distillate lubricating oil slack wax; and

c. about 1 to about wt. of a crystal modifying additive having an intrinsic viscosity in the range of about 0.05 to about 0.3 dl/g and selected from the group consisting of copolymers of 3 to 40 molar proportions of ethylene per molar proportion of an ethylenically unsaturated ester having the general formula:

wherein X is selected from the group consisting of hydrogen, and C, to C alkyl groups; and Y is selected from the group consisting of -OOCR and -COOR where R is C to C alkyl.

2. The composition of claim 1, wherein said lubricating oil has a boiling range of about 650F. to about 1 150F. A.E.T. and a viscosity at 2lOF. in the range of about 40 to about 180 SUS and said wax is a slack wax having a melting point in the range of about 100F. to about lF. and a viscosity at 210F. in the range of about 35 SUS to about SUS. derived from a distillate lubricating oil having a boiling range of about 650F. to about ll50F. A.E.T.

3. The composition of claim 1, wherein component (a) represents about 50 to about 70 wt. component (b) represents about 20 to about 40 wt. and component (0) represents about 3 to about 10 wt. of the total composition.

4. The composition of claim 1, wherein said crystal modifying additive is characterized by an intrinsic viscosity in the range of about 0.1 to about 0.29 dl/g.

5. The composition of claim 1, wherein said crystal modifying additive is a copolymer containing 3 to 20 molar proportions of ethylene per molar proportion of said ethylenically unsaturated ester.

6. The composition of claim 5, wherein said ester is a vinyl alcohol ester.

7. The composition of claim 6, wherein said ester is a vinyl alcohol ester of C to C monocarboxylic acid.

8. The composition of claim 7, wherein said ester is vinyl acetate. 

2. The composition of claim 1, wherein said lubricating oil has a boiling range of about 650*F. to about 1150*F. A.E.T. and a viscosity at 210*F. in the range of about 40 to about 180 SUS and said wax is a slack wax having a melting point in the range of about 100*F. to about 170*F. and a viscosity at 210*F. in the range of about 35 SUS to about 80 SUS. derived from a distillate lubricating oil having a boiling range of about 650*F. to about 1150*F. A.E.T.
 3. The composition of claim 1, wherein component (a) represents about 50 to about 70 wt. %, component (b) represents about 20 to about 40 wt. %, and component (c) represents about 3 to about 10 wt. % of the total composition.
 4. The composition of claim 1, wherein said crystal modifying additive is characterized by an intrinsic viscosity in the range of about 0.1 to about 0.29 Dl/g.
 5. The composition of claim 1, wherein said crystal modifying additive is a copolymer containing 3 to 20 molar proportions of ethylene per molar proportion of said ethylenically unsaturated ester.
 6. The composition of claim 5, wherein said ester is a vinyl alcohol ester.
 7. The composition of claim 6, wherein said ester is a vinyl alcohol ester of C2 to C5 monocarboxylic acid.
 8. The composition of claim 7, wherein said ester is vinyl acetate. 